If you love music while you jog, you know how important a good playlist can be to making sure you push yourself. Music can be really energizing, and the developers behind DjRun, a free Android app that pulls songs out of your library that match your running or walking pace, seem to agree. The app plays music designed to keep you on pace, speeds up with you, and slows down when you do so you don't have to skip tracks.

The app uses your phone's accelerometer as a pedometer, keeps track of how quickly you're walking or running, translates that into beats-per-minute, and pulls a song out of your phone's music library that matches your pace as closely as possible. The app displays your current pace and number of steps taken on-screen the whole time, and you can change the accuracy and sensitivity options in the settings if you find it's not matching songs with your stride very well. If you don't like a song DjRun selected, you can also manually change it, so you're never stuck with what it plays for you.

DjRun is free, but its best features come in the form of a $2.49 in-app upgrade. The "pro license" removes the ads, allows you to look up the tempo of other songs that may match your exercise style online (either via track metadata or ID3 tag), allows you to change the detected tempo of songs in your library by tapping the screen, lets you set your own playlist and see whether you can keep pace with it, and more.

If you've been looking for an music player that does more while you exercise than just plays songs, this might be a good option. Do you have a music player you use while you work out now? Share your thoughts—and alternative apps—in the comments below.